These days, news often breaks on Twitter: just look at the death of Whitney Houston or the killing of Osama Bin Laden. But one of the most interesting things about social media is what happens after the story breaks, as millions of people, networked via social media, analyze the story, share it and add their own thoughts, viewpoints and context. Tracked through hashtags, users around the world can see what conversations the Twitterverse is having about any given subject — and often, there’s plenty to say. So to tie together the year, Twitter has unveiled its “Pulse of the Planet” list for 2012, rounding up the most popular Twitter conversations across the world over the past 12 months. Here are the top five:

#London2012

With 10,500 athletes from 204 countries descending on London for the 16-day event, it’s hardly surprising that the 2012 Olympic Games were the most tweeted event of the year. Proud citizens of 204 countries took to Twitter to express their hopes and admiration for their representative athletes. Over the two weeks of the games, more than 150 million tweets were sent, from London and across the world, to share the glory and disappointment of the quest for gold medals. Usain Bolt’s victory in the men’s 200m sprint won gold for the most tweets during the athletic competition, with 80,000 updates sent in a single minute.

Thanks to all my real fans and people who believe in me. I am now a living legend that's for sure.

#Election2012

It was sort of like a sporting event in its own right: months of practice and buildup for one main event. The total number of tweets unleashed over the past 18 months of campaigning is unimaginable; during the Presidential debates alone, choice lines like “horses and bayonets,” “I like Big Bird,” and “binders full of women” prompted millions of tweets within hours. But Election Day, on Tuesday, November 6, proved a record-breaking day of conversation on Twitter in terms of politics. More than 31 million tweets were sent throughout the day, with a peak of 327,452 tweets per minute coming at 11:19 p.m. Eastern, when television networks began to call the race for President Obama.

The moment was capped off by a tweet that crushed all records ever set on Twitter: @BarackObama’s simple message of “Four more years.” accompanied by a photo of him and First Lady Michelle Obama, was retweeted 455,000 times that night and more than 815,000 times in total to date.

#Euro2012

But really, back to sports. Nothing unites the world — or Europe, at least – like football. (And we don’t mean the American kind in which players hardly even use their feet.) The Euro 2012 Football Championship held in Poland and Ukraine this summer played out on Twitter as much as on the field. Between June 8 and July 1, supporters of the 16 nations that qualified for the tournament expressed their excitement and disappointment to the tune of 16.5 million tweets over the three-week period.

During the final game of the championship, when Spain bested Italy 4-0, Twitter saw the biggest discussion of the whole event. More than 15,538 tweets were sent per second following Juan Mata’s fourth goal to cap off the game for the Spanish team. All told, 267,200 tweets were sent per minute as the game ended.

#SummerWars

In Japan, watching television is a social experience. The Japanese anime film Summer Wars was shown on Japanese television on July 20, and loyal watchers took to Twitter to share their enjoyment of the movie. Between 9 and 11 p.m. local time, 7.8 million tweets were sent referencing the film, according to BIGLOBE’s “Twipple Trend” report. One of the biggest tweet spikes, according to the report, was of the term “Koi-Koi,” a type of card game played in the film. Twitter also reported a huge simultaneous tweeting event when the film’s main character types the wordよろしくおねがいします (Yoroshiku onegaishimasu, meaning “thank you”), which inspired tens of thousands of watchers to type along.

#Sandy

From the seemingly endless run-up to the harrowing, powerless aftermath of Hurricane Sandy, Twitter recorded more than 20 million tweets about the storm. The Red Cross was mentioned on Twitter 30 times more than usual between Saturday and Tuesday. Mobile Twitter usage in New York City doubled around 9 p.m. Monday evening, just after Sandy ripped through, knocking out a power transformer that left much of lower Manhattan in darkness.

I don't give a damn about Election Day after what has happened here. I am worried about the people of New Jersey. #Sandy